This invention is directed to an improvement in an electric soldering iron. The improvement is directed to an elongated heating element which mates against and transfers heat to a tip member which includes an elongated heat receiving surface. The tip member includes an operative tip integrally formed as a portion of it. The main body of the tip member excluding the operative tip and the heating element are maintained within an elongated retaining tube with the operative tip extending out of one end of the retaining tube. The retaining tube is mounted to the handle of the soldering iron to maintain the heating element and the tip member in their respective positions.
Presently existing soldering irons usually incorporate a relatively large thermal mass in association with a heating element. The thermal mass receives heat from the heating element and supplies it to a tip. Because of the bulk of the thermal mass used in these irons, there is a time lag which is necessary for the heating element to heat up this large thermal mass. Once heated, the large thermal mass supplies heat to the tip. The tip withdraws heat from the thermal mass as soldering joints are formed with the soldering iron.
Generally, the soldering irons having the large thermal masses noted in the previous paragraph are somewhat inefficient in transferring heat from the heating element to the thermal mass. This is basically because of the design of the thermal mass and the heating elements themselves. The heat transfer between the heating element and the larger thermal mass is regulated in a certain degree between the amount of surface contact between the same. Since the bulk of the large thermal mass is internal to the mass and does not form a part of its outside surface, the heat transfer between the heating element and the thermal mass is proportionately low compared to the amount of thermal mass.
Once heated, the large thermal mass of the above noted soldering irons do retain a considerable amount of heat. However, because of the large mass, much of this heat is available to go back to the handle. In order to prevent this, bulky handles which contain a lot of shielding or insulation must be utilized. This, unfortunately, is a disadvantage to the user of the device wherein minimum bulk and weight of the soldering iron is desirable. Further, once the heat is withdrawn from the large thermal mass, it takes considerable heat-up time to once again heat up the thermal mass to a point wherein the tip is hot enough to form the necessary soldering joints. it is thus evident that the presently available soldering irons which incorporate these large thermal masses are disadvantageous to the user because of bulk and because of their heat up time.
Further, the soldering irons noted above usually have a replaceable tip which screws onto the thermal mass. Both the tip and the thermal mass are generally made of a high heat conductive material such as copper or a copper alloy. The screw threads, therefore, between the tip and the large thermal mass of necessity are also made of this alloy and must be plated. Plating, however, is not too effective in threaded areas. During the soldering procedure, because of the use of fluxes and the like, fumes are generated which interact with the metallic material of the tips and the thermal mass. Both the presence of the fumes are the repetitive cycling between hot and cold of both the tips and the mass tends to fuse the tips to the mass. When it becomes necessary to change the tips because of wear to the tip or the desirability of using a tip having a different design, many times the user of the above noted soldering irons finds it impossible to remove the tip from the iron because of the fusing of the metal of the tip with the metal of the thermal mass.